This invention relates to bar code systems and methods and their method of use, and, more particularly, to placing primary and secondary information into a bar code, removing such information from a bar code and using the extracted information to control a manufacturing process.
Bar codes and similar code recording arrangements are widely used today to mark objects in order to provide rapidly readable codes containing information relating to the object, such as, its identity or its price. For example, see The Bar Code Book: Reading, Printing, and Specification of Bar Code Symbols, by R. Palmer (Helmers Publishing, Inc., 1991); Lines of Communication: Bar Code and Data Collection Technology For the 90""s, by C. Harmon (Helmers Publishing, Inc., 1994); Applying Industrial Bar Coding, by T. Sobczak (Society of Manufacturing Engineers, 1985); or Barcodes Galore: Maximize Productivity, by H. Burke (Tevaki Associates, 1992). Such codes usually consist of a horizontal series of printed vertical parallel bars of varying widths and spacings arranged to produce a particular reflectivity pattern when the bars are scanned sequentially in a straight line with a light beam, such as, a laser beam, in a direction transverse to the orientation of the bars.
Most continuous manufacturing processes perform different operations at different stations in the assembly line. For example, in an engine block assembly line, a hole is drilled at one station, tapped at another and studded at yet another. Normally, a bar code may be used to store primary information relating to the product""s identification, inventory, and pricing, etc. While it is known to provide such process information in a bar code, nonetheless, it is not known to provide such product-specific, process-specific tasks as a type of secondary information stored in a single bar code along with the aforesaid general primary information. Accordingly, there is a need for and it is an object of the present invention to provide a method for using the bar code having primary general product information and secondary process-specific information in a single bar code and a method for using such bar codes to control a manufacturing process involving object dependent tasks that rely on the secondary, process-specific information embedded within the primary bars.
Heretofore, recording both primary product-specific and process-specific information in bar codes has required the use of multiple bar codes (i.e. one bar code defining the primary information and one or more additional, separate bar codes defining the secondary information). Conventional bar codes have severe spatial limitations and are able to store only a limited amount of information. A problem with using multiple bar codes on a part or product, however, has been that they occupy substantial space and reading is complicated. The prior art discloses many methods for increasing storage density. For examples of such systems, see the following U.S. Pat. Nos.: 4,889,367; 5,128,528; 5,153,418; 5,170,044; 5,296,693; 5,189,292; 5,355,001; and 5,481,100.
However, none of the known prior art is designed to be downward compatible with the conventional bar code technology (i.e. UPC symbology) while at the same time increasing the storage density. Therefore, there is a need for and it is an object of the present invention to provide an improved method for more efficiently encoding and decoding both primary and secondary information in a single bar code in a manner which not only increases its storage density, but also is downwardly compatible with conventional bar code reading/scanning technology.
Some methods of using parity checking and other error correcting schemes in bar codes are disclosed in the prior art. For example, see the following U.S. Pat. Nos.: 5,288,986 and 5,436,437. However, these methods are complex and cumbersome to use. Accordingly, there is a need for and it is an object of the present invention to provide a method to simplify checking, tracking, and labeling procedures.
The prior art teaches that bar codes are scanned and read by decoding and reading the entire bar code. For examples of such decoding technology using linear scanning methods, see U.S. Pat. Nos.: 3,902,049; 4,074,114; 4,578,570; 5,357,094; 5,412,198; 5,486,689; and 5,514,858. For examples of decoding technology using image processing or image analysis, see U.S. Pat. Nos.: 4,578,570, 4,988,852; 5,276,315; 5,296,690; 5,304,787; 5,367,578; 5,428,211; 5,468,945; and 5,489,769. However, there is a need for and it is an object of the present invention to provide a method of selectively reading only a part or fraction of a bar code for certain selected information to provide a relatively simple and more cost-effective way of reading a bar code having both primary and secondary/auxiliary information.
It is a further specific object of the invention to provide a method for reading a bar code in one direction to scan in primary information and in another direction to scan in secondary information.
One aspect of the invention is a method of reading a bar code having an area with primary and secondary information encoded therein which includes the steps of scanning the area in one direction to decode the primary information, and scanning the area in another direction to decode the secondary information.
One feature of this aspect of the invention is use of a plurality of spaced apart primary bars in the scanned area. In this form of the invention the step of scanning the primary bars in the one direction includes locating a direction perpendicular to the primary bars, scanning the primary bars in the perpendicular direction, and interpreting the decoded primary information obtained. In this aspect of the invention step of scanning the bars in the other direction to decode the secondary information includes determining a direction perpendicular to the bars, identifying each bar with secondary information encoded therein, and scanning selected ones of the bars in the other direction orthogonal to the one direction.
Another feature of this aspect of the invention includes locating a direction perpendicular to the primary bars by scanning the primary bars with a scan beam in a scan path in a plane of the bars while the path is rotated about one axis until the path crosses a start or stop code of the bar code thereby identifying a crossing length of the bar code, shifting the axis of rotation to a point within the bar code substantially at the center of the crossing length of the bar code, and continuing to rotate the scan path until both a start and stop code of the bar code are crossed in a minimum crossing length.
A still further feature of this aspect of the invention includes the step of scanning the bars in the other direction by positioning a scan beam path parallel to the other direction of encoded secondary information, moving the scan beam in the other direction to one end of the area, rotating the scan beam to a direction opposite the other direction, scanning the area of encoded secondary information in the opposite direction along an entire length of a bar, and interpreting the secondary information obtained.
A second aspect of the invention is a system for reading a bar code having areas with primary and secondary information encoded therein which includes a computer system for controlling the reading of the bar code, a horizontal driver and a vertical driver coupled to the computer system, a horizontal actuator coupled to the horizontal driver and the computer system for controlling horizontal directional scanning of the bar code, a vertical actuator coupled to the vertical driver and the computer system for controlling vertical directional scanning of the bar code, a laser for producing a scanning beam, optics coupled to the horizontal actuator and the vertical actuator for controlling the beam of the laser onto the bar code in a predetermined scanning pattern to receive reflected light from the bar code representative of the primary information encoded therein in one direction and the secondary information encoded therein in another direction, a photodetector coupled to the optics for producing an analog voltage output corresponding to the intensity of the measured reflected light received by the photodetector via the optics, and an analog to digital converter coupled to the photodetector and the computer system for converting the analog voltage output to a digital signal which is coupled to the computer system for interpretation.
A third aspect of the invention includes a method of using a bar code having areas with primary information and secondary information encoded therein to control work to be performed on a workpiece which includes the steps of applying the bar code to the workpiece, scanning the bar code and decoding the primary information in the bar code to identify the workpiece, determining the areas of the bar code with secondary information describing the work to be performed on the workpiece, scanning selected ones of those areas of the bar code having the desired secondary information, commanding selected ones of a plurality of work stations to perform work on the workpiece according to the decoded secondary information, and performing the commanded work on the workpiece at the assigned stations.